Molecular phylogeny reveals food plasticity in the evolution of true ladybird beetles (Coleoptera: Coccinellidae: Coccinellini)

Abstract

BackgroundThe tribe Coccinellini is a group of relatively large ladybird beetles that exhibits remarkable morphological and biological diversity. Many species are aphidophagous, feeding as larvae and adults on aphids, but some species also feed on other hemipterous insects (i.e., heteropterans, psyllids, whiteflies), beetle and moth larvae, pollen, fungal spores, and even plant tissue. Several species are biological control agents or widespread invasive species (e.g., Harmonia axyridis (Pallas)). Despite the ecological importance of this tribe, relatively little is known about the phylogenetic relationships within it. The generic concepts within the tribe Coccinellini are unstable and do not reflect a natural classification, being largely based on regional revisions. This impedes the phylogenetic study of important traits of Coccinellidae at a global scale (e.g. the evolution of food preferences and biogeography).ResultsWe present the most comprehensive phylogenetic analysis of Coccinellini to date, based on three nuclear and one mitochondrial gene sequences of 38 taxa, which represent all major Coccinellini lineages. The phylogenetic reconstruction supports the monophyly of Coccinellini and its sister group relationship to Chilocorini. Within Coccinellini, three major clades were recovered that do not correspond to any previously recognised divisions, questioning the traditional differentiation between Halyziini, Discotomini, Tytthaspidini, and Singhikaliini. Ancestral state reconstructions of food preferences and morphological characters support the idea of aphidophagy being the ancestral state in Coccinellini. This indicates a transition from putative obligate scale feeders, as seen in the closely related Chilocorini, to more agile general predators.ConclusionsOur results suggest that the classification of Coccinellini has been misled by convergence in morphological traits. The evolutionary history of Coccinellini has been very dynamic in respect to changes in host preferences, involving multiple independent host switches from different insect orders to fungal spores and plants tissues. General predation on ephemeral aphids might have created an opportunity to easily adapt to mixed or specialised diets (e.g. obligate mycophagy, herbivory, predation on various hemipteroids or larvae of leaf beetles (Chrysomelidae)). The generally long-lived adults of Coccinellini can consume pollen and floral nectars, thereby surviving periods of low prey frequency. This capacity might have played a central role in the diversification history of Coccinellini.Electronic supplementary materialThe online version of this article (doi:10.1186/s12862-017-1002-3) contains supplementary material, which is available to authorized users.

Mitogenome evolution in ladybirds: Potential association with dietary adaptation

“…Traditionally, the classification system of Coccinellidae includes six or seven subfamilies, although only two subfamilies (Coccinellinae and Microweiseinae) were found to be truly monophyletic based on molecular and morphological data (Giorgi et al, 2009;Magro, Lecompte, Magne, Hemptinne, & Crouau-Roy, 2010;Seago, Giorgi, Li, & Slipinski, 2011). Dietary shifts in ladybirds have been associated with changes in physiological metabolism and ecological adaptation (Escalona, Zwick, et al, 2017;Giorgi et al, 2009;Li, Pan, Clercq, Ślipiński, & Pang, 2016). Three major types of feeding habits are generally recognized for coccinellids: predatory (most coccinellid species), phytophagous (those feeding on plants, e.g., Henosepilachna vigintioctopunctata) and mycetophagous (those feeding on fungi, e.g., Halyzia sedecimguttata).…”

Puncture vs. reflex bleeding: Haemolymph composition reveals significant differences among ladybird species (Coleoptera: Coccinellidae), but not between sampling methods

“…It is also possible that differences between species are not related to their invasive status, but are a result of the evolutionary history of a species. Based on the recent phylogenetic analyses of true ladybirds (Magro et al, 2010;Escalona et al, 2017), the genera Harmonia and Ceratomegilla are closely related to each other, whereas the genus Coccinella belongs to a different clade.…”

A comprehensive phylogeny of flat bark beetles (Coleoptera: Cucujidae) with a revised classification and a new South American genus

“…To calculate MLBS, multiple heuristic searches (20) were carried out for each of the 200 bootstrap pseudoreplicates to increase the accuracy of the estimate through increased search effort (e.g. Regier et al, 2013;Escalona et al, 2017). This is not implemented in iq-tree and the following approach was used to achieve the more accurate MLBS.…”